It sounds as if the tape drive is being seen by both Windows and BE, which is good. But you are missing the robotic library.
So, the next question is does Windows see the robot? Look in Windows Device manager, under the "Medium Changer Device" and what (if anything) do you see? You should see an entry for "unknown medium changer". If you see something else, I would suggest uninstalling and deleting the IBM driver. If you don't see anything, then you likely have some hardware or configuration issues to resolve in the HBA or the tape library.
Then reboot the server and see if the robotic library is dscovered correctly by Windows. Once Windows discovers the robotic library properly, then Backup Exec should automatically discover the robotic library and make it usable to you.
